Guaranteed delivery of application layer messages by a network element

ABSTRACT

A method is disclosed by which network elements such as packet routers and packet switches guarantee the delivery of application layer messages within a network. According to one aspect, a first network element retrieves an application layer message from a source message queue, adds a message identifier to the application layer message, encapsulates the application layer message into data packets, and sends the data packets toward a destination application. A second network element intercepts the data packets, determines the application layer message from payload portions of the data packets, determines the message identifier from the application layer message, stores the application layer message in a destination message queue, generates an acknowledgement message that contains the message identifier, and sends the acknowledgement message toward a source application. The first network element intercepts the acknowledgement message and concludes that the application layer message within the matching message identifier was successfully delivered.

FIELD OF THE INVENTION

The present invention generally relates to network elements in computernetworks. The invention relates more specifically to a method andapparatus by which network elements guarantee the delivery ofapplication layer messages within a network.

BACKGROUND

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not prior art to the claims in this application andare not admitted to be prior art by inclusion in this section.

In a business-to-business environment, applications executing oncomputers commonly communicate with other applications that execute onother computers. For example, an application “A” executing on a computer“X” might send, to an application “B” executing on a computer “Y,” amessage that indicates the substance of a purchase order.

Computer “X” might be remote from computer “Y.” In order for computer“X” to send the message to computer “Y,” computer “X” might send themessage through a computer network such as a local area network (LAN), awide-area network (WAN), or an inter-network such as the Internet. Inorder to transmit the message through such a network, computer “X” mightuse a suite of communication protocols. For example, computer “X” mightuse a network layer protocol such as Internet Protocol (IP) inconjunction with a transport layer protocol such as Transport ControlProtocol (TCP) to transmit the message.

Assuming that the message is transmitted using TCP, the message isencapsulated into one or more data packets; separate portions of thesame message may be sent in separate packets. Continuing the aboveexample, computer “X” sends the data packets through the network towardcomputer “Y.” One or more network elements intermediate to computer “X”and computer “Y” may receive the packets, determine a next “hop” for thepackets, and send the packets towards computer “Y.”

For example, a router “U” might receive the packets from computer “X”and determine, based on the packets being destined for computer “Y,”that the packets should be forwarded to another router “V” (the next“hop” on the route). Router “V” might receive the packets from router“U” and send the packets on to computer “Y.” At computer “Y,” thecontents of the packets may be extracted and reassembled to form theoriginal message, which may be provided to application “B.” Applications“A” and “B” may remain oblivious to the fact that the packets wererouted through routers “U” and “V.” Indeed, separate packets may takedifferent routes through the network.

A message may be transmitted using any of several application layerprotocols in conjunction with the network layer and transport layerprotocols discussed above. For example, application “A” may specify thatcomputer “X” is to send a message using Hypertext Transfer Protocol(HTTP). Accordingly, computer “X” may add HTTP-specific headers to thefront of the message before encapsulating the message into TCP packetsas described above. If application “B” is configured to receive messagesaccording to HTTP, then computer “Y” may use the HTTP-specific headersto handle the message.

In addition to all of the above, a message may be structured accordingto any of several message formats. A message format generally indicatesthe structure of a message. For example, if a purchase order comprisesan address and a delivery date, the address and delivery date may bedistinguished from each other within the message using messageformat-specific mechanisms. For example, application “A” may indicatethe structure of a purchase order using Extensible Markup Language(XML). Using XML as the message format, the address might be enclosedwithin “<address>” and “</address>” tags, and the delivery date might beenclosed within “<delivery-date>” and “</delivery-date>” tags. Ifapplication “B” is configured to interpret messages in XML, thenapplication “B” may use the tags in order to determine which part of themessage contains the address and which part of the message contains thedelivery date.

As is discussed above, a message may be divided into portions, and eachportion may be transmitted in a separate IP packet toward the message'sdestination. The TCP protocol implements mechanisms for ensuring that IPpackets may be assembled in their proper order relative to each other,and that no IP packet will be duplicated.

When a destination application (e.g., application “B” in the exampleabove) receives a TCP packet, the destination application sends anacknowledgment back toward the packet's source. The acknowledgementidentifies the packet by the packet's sequence number. If the sourceapplication (e.g., application “A” in the example above) receives theacknowledgement within a specified interval of time after sending thecorresponding packet, then the source application will be confident thatthe destination application received the packet. As a result, the sourceapplication does not need to re-send the packet. Alternatively, if thesource application does not receive the acknowledgement within aspecified interval of time after sending the corresponding packet, thenthe source application re-sends the packet. The packet may be re-sentuntil the source application receives an acknowledgment.

Under some circumstances, a proxy device receives packets from a sourceapplication and then forwards the packets to the destinationapplication. Under these circumstances, the proxy device sendsacknowledgements back to the source application. It is possible that theproxy device might send an acknowledgment to the source application, butthe packet corresponding to the acknowledgment might not successfullyreach the destination application. For example, this might happen if theconnection between the proxy device and the destination application isbroken, or if the destination application fails. Under thesecircumstances, the source application still will receive theacknowledgement from the proxy device and, consequently, will notre-send the packet even though the packet never reached the destinationapplication.

Thus, under some circumstances, such as those described above, the TCPprotocol does not guarantee that a particular TCP packet actually willreach a destination application. As a result, there is no guarantee thata message at least partially contained within the particular TCP packetwill reach the destination application.

A technique for guaranteeing that a message sent from a sourceapplication will be received by a destination application is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a block diagram that illustrates an overview of one embodimentof a system in which network elements collectively guarantee thedelivery of application layer messages;

FIG. 2A depicts a flow diagram that illustrates an overview of oneembodiment of a method of reliably sending messages using a messagequeue and message identifiers contained within application layermessages;

FIG. 2B depicts a flow diagram that illustrates an overview of oneembodiment of a method of guaranteeing message delivery using a messagequeue and message identifiers contained within acknowledgement messages;

FIGS. 3A-B depict a flow diagram that illustrates one embodiment of amethod of classifying application layer messages into messageclassifications and performing actions that are associated with thosemessage classifications;

FIG. 4 depicts a sample flow that might be associated with a particularmessage classification;

FIG. 5 is a block diagram that illustrates a computer system upon whichan embodiment may be implemented;

FIG. 6 is a block diagram that illustrates one embodiment of a router inwhich a supervisor blade directs some packet flows to an AONS bladeand/or other blades;

FIG. 7 is a diagram that illustrates the various components involved inan AONS network according to one embodiment;

FIG. 8 is a block diagram that depicts functional modules within anexample AONS node;

FIG. 9 is a diagram that shows multiple tiers of filtering that may beperformed on message traffic in order to produce only a select set oftraffic that will be processed at the AONS layer;

FIG. 10 is a diagram that illustrates the path of a message within anAONS cloud according to a cloud view;

FIG. 11A and FIG. 11B are diagrams that illustrate a request/responsemessage flow;

FIG. 12A and FIG. 12B are diagrams that illustrate alternativerequest/response message flows;

FIG. 13 is a diagram that illustrates a one-way message flow;

FIG. 14 is a diagram that illustrates alternative one-way message flows;

FIG. 15A and FIG. 15B are diagrams that illustrate a request/responsemessage flow with reliable message delivery;

FIG. 16 is a diagram that illustrates a one-way message flow withreliable message delivery;

FIG. 17 is a diagram that illustrates synchronous request and responsemessages;

FIG. 18 is a diagram that illustrates a sample one-way end-to-endmessage flow;

FIG. 19 is a diagram that illustrates message-processing modules withinan AONS node;

FIG. 20 is a diagram that illustrates message processing within AONSnode;

FIG. 21, FIG. 22, and FIG. 23 are diagrams that illustrate entitieswithin an AONS configuration and management framework; and

FIG. 24 is a diagram that illustrates an AONS monitoring architecture.

DETAILED DESCRIPTION

A method and apparatus for reducing the sizes of application layermessages in a network element is described. In the followingdescription, for the purposes of explanation, numerous specific detailsare set forth in order to provide a thorough understanding of thepresent invention. It will be apparent, however, to one skilled in theart that the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring thepresent invention.

Embodiments are described herein according to the following outline:

-   -   1.0 General Overview    -   2.0 Structural and Functional Overview    -   3.0 Implementation Examples        -   3.1 Multi-Blade Architecture        -   3.2 Message Classification        -   3.3 Action Flows        -   3.4 AONS Examples            -   3.4.1 AONS General Overview            -   3.4.2 AONS Terminology            -   3.4.3 AONS Functional Overview            -   3.4.4 AONS System Overview            -   3.4.5 AONS System Elements            -   3.4.6 AONS Example Features            -   3.4.7 AONS Functional Modules            -   3.4.8 AONS Modes of Operation            -   3.4.9 AONS Message Routing            -   3.4.10 Flows, Bladelets™, and Scriptlets™            -   3.4.11 AONS Services            -   3.4.12 AONS Configuration and Management            -   3.4.13 AONS Monitoring            -   3.4.14 AONS Tools    -   4.0 Implementation Mechanisms—Hardware Overview    -   5.0 Extensions and Alternatives        1.0 General Overview

The needs identified in the foregoing Background, and other needs andobjects that will become apparent for the following description, areachieved in the present invention, which, in one aspect, comprises asystem in which network elements guarantee that application layermessages will be delivered. As used herein, an “application layermessage” is a message that is generated by an application—although themessage may also contain content supplied by one or more users—and whichdoes not necessarily include the protocol headers that may be appendedin the course of the transmission of that message. For example, anapplication layer message may be an XML document that does not includean HTTP header that is later appended to the front of that document.

According to one embodiment, a source application inserts a firstapplication layer message into a source message queue in a transactionalmanner; this guarantees that the first application layer message will beinserted into the source message queue. A first network element thatacts as the network's entry node, such as a network switch, router,proxy device, network appliance and/or a device that is attached orconnected to a switch or router and that performs OSI Layer 2 and aboveprocessing, including packet- and message-level processing, proactivelyretrieves the first application layer message from the source messagequeue without removing the first application layer message from thesource message queue. To the first application layer message, the firstnetwork element generates a universally unique message identifier andadds that to the first application layer message. The first networkelement establishes a mapping between the message identifier and thefirst application layer message. The first network element thenencapsulates the first application layer message into data packets, suchas IP packets, and sends the data packets toward a destinationapplication.

A second network element, such as a network switch, router, or proxydevice, which acts as the exit point of the network, is sitting betweenthe network route and the destination application, intercepts orotherwise receives the data packets. The second network elementdetermines the first application layer message, which is collectivelycontained in payload portions of the data packets. The second networkelement determines the message identifier, which is contained in thefirst application layer message. The second network element determineswhether the message identifier is already contained in a messageidentifier queue. If the message identifier is already contained in themessage identifier queue, then the second network element drops thefirst application layer message so that the first application layermessage is not delivered to the destination application; this preventsduplicate messages from being delivered to the destination application.

Alternatively, if the message identifier is not already contained in themessage identifier queue, then the second network element inserts themessage identifier into the message identifier queue and inserts thefirst application layer message into a destination message queue in atransactional manner; this guarantees that the first application layermessage will be inserted into the destination message queue. In someembodiments, in response to a determination that the message identifierqueue does not contain the message identifier, the message identifier isstored in the message identifier queue, together with the storing of thefirst application message in the application layer message queueatomically. The second network element also generates a secondapplication message (which we call ACK message later on) thatacknowledges receipt of the first application layer message. The secondapplication layer message (ACK message) contains the message identifierof the first application message. The second network element thenencapsulates the ACK message into data packets, such as IP packets, andsends the data packets towards the first network element.

The destination application proactively retrieves the first applicationlayer message from the destination message queue in a transactionalmanner. After the destination application has retrieved the firstapplication layer message from the destination message queue, thedestination application removes the first application layer message fromthe destination message queue.

If the first network element, which sits in the network route to thesource application, intercepts or otherwise receives the data packetssent from the second network element, then the first network elementdetermines the ACK message, which is collectively contained in payloadportions of the data packets. The first network element extracts themessage identifier from the ACK message. From the source message queue,the first network element removes the first application layer message,which is mapped to the message identifier. The successful delivery ofthe first application layer message has been guaranteed.

Alternatively, if a specified amount of time passes after the firstnetwork element sent the first application layer message without thefirst network element receiving the data packets sent from the secondnetwork element, then the first network element concludes that the firstapplication layer message needs to be re-sent. The first network elementre-sends the first application layer message, including the messageidentifier, toward the destination application in the same manner asdescribed above. Unless some problem permanently prevents the deliveryof the first application layer message, the first network elementeventually will receive the ACK message from the second network element.

In other aspects, the invention encompasses methods performed by thefirst and second network elements in the foregoing system, andcomputer-readable media configured to carry out the steps of suchmethods.

2.0 Structural and Functional Overview

FIG. 1 is a block diagram that illustrates an overview of one embodimentof a system 100 in which one or more of network elements 102 and 106collectively guarantee the delivery of application layer messages (alsoreferred to herein simply as “messages”). Network elements 102 and 106may be proxy devices or network switches or routers, for example.Network elements 102 and 106 may be network routers such as router 600depicted in FIG. 6 below, for example.

A client application 110 is coupled communicatively to persistentstorage 136. Persistent storage 136 is coupled communicatively withnetwork element 102. Persistent storage 136 may be incorporated into adevice that is separate from network element 102.

A server application 112 is coupled communicatively to persistentstorage 138. Persistent storage 138 is communicatively coupled withnetwork element 106. Persistent storage 138 may be incorporated into adevice that is separate from network element 106. Client application 110and server application 112 are separate processes executing on separatecomputers.

Network elements 102 and 106 are coupled communicatively with a network116. Network 116 is a computer network, such as, for example, a localarea network (LAN), wide area network (WAN), or internetwork such as theInternet. Network 116 may contain additional network elements such asrouters.

Persistent storage 136 and persistent storage 138 are repositories thatpersistently store data. Persistent storage 136 and persistent storage138 may be hard disk drives of devices that are separate from networkelements 102 and 106, for example. Persistent storage 136 and persistentstorage 138 may comprise databases that organize the data stored thereonin a relational manner. Such databases may allow data to be stored in atransactional manner, so that either all data belonging to a particulartransaction is committed, or no data belonging to the particulartransaction is committed.

Transactional message queues 130 and 134 are used to guaranteeend-to-end delivery. Client application 110 (the “sender application”)addresses messages to server application 112 and inserts the messagesinto a source message queue 130 that is located on persistent storage136. Thus, client application 110 “pushes” messages into source messagequeue 130 by enqueueing the messages. Messages may be XML documents,Java Messaging Service (JMS) messages, or other kinds of messages, forexample. After client application 110 has pushed a message into sourcemessage queue 130, client application 110 commits, into a client-sidedatabase, a transaction with which the message is associated. Networkelement 102 (the “client proxy” or “CP”) proactively retrieves messagesfrom source message queue 130 by transactionally dequeueing themessages, inserts message identifiers into those messages, and sendsthose messages within data packets toward server application 112 (the“receiver application”). Thus, network element 102 “pulls” messages fromsource message queue 130 and sends the messages through network 116.

Network element 106 (the “server proxy” or “SP”) intercepts the datapackets that contain the messages. For each set of one or more datapackets that contains a separate message, network element 106 assemblesthe data packets in that set to determine the message contained therein.For each such message, network element 106 determines whether themessage's identifier is already contained in a message identifier queue132 that is located on persistent storage 138. If the message'sidentifier is already contained in message identifier queue 132, thennetwork element 106 does not store the message in a destination messagequeue 134 that is located on persistent storage 138. However, if themessage's identifier is not contained in message identifier queue 132,then network element 106 stores the message's identifier in messageidentifier queue 132 and stores the message itself in destinationmessage queue 134. Thus, network element 106 “pushes” the message intodestination message queue 134 by enqueueing the message and “pushes” themessage's identifier into message identifier queue 132. After networkelement 106 has pushed the message and message identifier in thismanner, client application 110 commits, into a server-side database, atransaction with which the message is associated.

After network element 106 has successfully pushed the message intodestination message queue 134, network element 106 generates anacknowledgement message (ACK) that contains the message's identifier.Network element 106 sends the ACK within data packets toward networkelement 102.

Network element 102 intercepts the data packets that contain the ACK.Network element 102 determines the message identifier that is containedin the ACK. Network element 102 commits, into a client-side database, atransaction with which the message is associated. Network element 102removes, from source message queue 130, the message that corresponds tothe message identifier. Because the message is removed from sourcemessage queue 130, network element 102 will not re-send the messagethereafter.

Based on the contents of the message, network element 106 may determinea classification for the message and perform one or more actions thatare associated with the message's classification. Examples of some ofthese actions are described in further detail below with reference toFIGS. 3A-3B. Server application 112 (the “receiver application”)proactively retrieves messages from destination message queue 134 bydequeueing the messages. Server application 112 commits, into aserver-side database, a transaction with which the message isassociated. Server application 112 removes such retrieved messages fromdestination message queue 134.

Each message in source message queue 130 may be associated with a timeat which that message was most recently sent (the “message's sendingtime”). For each message remaining in source message queue 130, when aspecified amount of time passes since the message's sending time,network element 102 re-sends the message and updates the message'ssending time. Network element 102 periodically re-sends messagesremaining in source message queue 130 until network element 102 receivescorresponding acknowledgement messages that indicate the correspondingmessage identifiers.

FIG. 2A depicts a flow diagram 200A that illustrates an overview of oneembodiment of a method of reliably sending messages using a messagequeue and message identifiers contained within application layermessages. For example, network element 102 may perform such a method.

In block 202, a network element retrieves an application layer messagefrom a message queue. For example, network element 102 may retrieve anapplication layer message from source message queue 130. The applicationlayer message may be an XML document or a JMS message, for example. Theapplication layer message might indicate the substance of a purchaseorder, for example. Network element 102 may periodically poll sourcemessage queue 130 for messages that have not yet been sent, and retrievethose messages.

In block 204, a message identifier is added to the application layermessage. For example, network element 102 may add, to the applicationlayer message retrieved from source message queue 130, a number thatuniquely identifies the application layer message. For example, if themessage is an XML document, then network element 102 may add, to the XMLdocument, an XML element such as “<message ID=‘123’>”. The messageidentifier is contained within the message itself, rather than in aprotocol header that precedes the message. In one embodiment, the numberis added to the copy of the message that is stored in source messagequeue 130, so that if the message is re-sent, the message will bere-sent with the same message identifier.

In block 206, the application layer message is sent toward a destinationapplication. For example, network element 102 may encapsulate theapplication layer message into one or more TCP packets and send thepackets toward server application 112. In one embodiment, each messagein source message queue 130 is associated with an indication of themessage's ultimate destination. For example, each message may beassociated with a separate destination IP address, and network element102 may send each message toward the destination IP address that isassociated with that message.

In block 208, it is determined whether at least a specified amount oftime has passed since the application layer message was sent. Forexample, when network element 102 sends an application layer message,network element 102 may associate the application layer message with atimestamp within source message queue 130. Network element 102 maydetermine whether a specified amount of time has elapsed since aparticular message was sent by comparing the message's associatedtimestamp with the current time. If at least the specified amount oftime has elapsed, then control passes to block 206, in which theapplication layer message is re-sent toward the destination application.Otherwise, control passes to block 210.

In block 210, it is determined whether an acknowledgement message thatcontains the message identifier has been received. For example, networkelement 102 may receive one or more data packets that collectivelycontain, in their payload portions, an acknowledgement message thatcontains a message identifier. Such an acknowledgement message may begenerated by network element 106, for example, as is described belowwith reference to FIG. 2B.

Network element 102 may assemble the data packets to determine theacknowledgement message and the message identifier contained therein.Network element 102 is capable of determining application layer messageboundaries, so, in one embodiment, network element 102 may performoperations on an application layer message contained in a stream, orportions thereof, even if network element 102 has not yet received allof the data packets that contain all of the portions of the applicationlayer message. For example, an acknowledgement message might be an XMLdocument that contains an XML element such as “<acknowledgementID=‘123’>”. Network element 102 may compare the acknowledgementmessage's identifier with the application layer message's identifier. Ifthere is a match, then network element 102 may conclude that theacknowledgement message that corresponds to the application layermessage has been received. In this case, control passes to block 212.Otherwise, if the acknowledgement message that corresponds to theapplication layer message has not yet been received, then control passesback to block 208.

In block 212, the application layer message is removed from the messagequeue. For example, network element 102 may remove the application layermessage from source message queue 130. The receipt of theacknowledgement message that contains the application layer message'sidentifier signifies that the message has been delivered reliably.Thereafter, due to the removal of the application layer message fromsource message queue 130, network element 102 will not re-send theapplication layer message.

FIG. 2B depicts a flow diagram 200B that illustrates an overview of oneembodiment of a method of guaranteeing message delivery using a messagequeue and message identifiers contained within acknowledgement messages.For example, network element 106 may perform such a method.

In block 220, data packets are intercepted or otherwise received by anetwork element. For example, network element 106 may intercept one ormore TCP data packets that were sent toward server application 112 bynetwork element 102.

In block 222, an application layer message is determined from payloadportions of the data packets. For example, network element 106 mayassemble the data packets that are destined for server application 112.Network element 106 may inspect the contents of the payload portions ofthe assembled data packets to determine an application layer messagethat client application 110 is trying to send to server application 112.The message may be, for example, a purchase order formatted according toXML. The message might follow an HTTP header, for example.

In block 224, a message identifier is determined from the applicationlayer message. For example, network element 106 may look within theapplication layer message for a specified XML element that indicates amessage identifier. The message identifier is contained within theapplication layer message itself, rather than a protocol header thatprecedes the application layer message. For example, network element 106might find, within the application layer message, an XML element such as“<message ID=‘123’>” that network element 102 added to the message. Inthis case, the message identifier is “123”.

In block 226, it is determined whether the message identifier iscontained in a message identifier queue. For example, network element106 may query message identifier queue 132 to determine whether messageidentifier queue 132 contains the message identifier. If the messageidentifier queue contains the message identifier, then control passes toblock 228. Otherwise, control passes to block 230.

In block 228, the application layer message is dropped. The applicationlayer message is not stored in a destination message queue as describedbelow with reference to block 230. The presence of the messageidentifier within message identifier queue 132 signifies that theapplication layer message duplicates a message that has already beendelivered; such duplicates may occur when an acknowledgement messagefails to reach a “sending” network element in a timely manner, causingthe sending network element to re-send a message. Because the message isa duplicate, the message should not be stored in destination messagequeue 134, where the message would be retrieved by server application112. Control passes to block 234.

Alternatively, in block 230, the application layer message is insertedinto a message queue. For example, network element 106 may insert theapplication layer message into destination message queue 134. Serverapplication 112 may proactively retrieve the application layer messagefrom destination message queue 134. Control passes to block 232.

In block 232, the message identifier is inserted into a messageidentifier queue. For example, network element 106 may insert themessage identifier into message identifier queue 132. This preventsduplicate application layer messages with the same message identifierfrom being inserted into destination message queue 134. Control passesto block 234.

In block 234, an acknowledgement application layer message(“acknowledgement message”) is generated and sent toward the sourceapplication from which the original application layer messageoriginated. The acknowledgement message contains the message identifierthat was contained in the corresponding application layer message. Forexample, network element 106 may generate an acknowledgement messagethat contains an XML element such as “<acknowledgement ID=‘123’>”,assuming that the corresponding application layer message indicated amessage identifier of “123”. Network element 106 may encapsulate theacknowledgement message within one or more TCP packets, and send the TCPpackets toward client application 110.

Although, in one embodiment, data packets that contain application layermessages are addressed to client application 110 and server application112, in an alternative embodiment, such data packets are addressed tonetwork element 102 and network element 106. This may be the case whennetwork element 102 and network element 106 are both proxy devices, forexample.

Techniques are described above in relation to application layer messagessent from client application 110 toward server application 112. Theabove techniques are also applicable to application layer message sentfrom server application 112 toward client application 110. For example,the techniques described above may be used to guarantee the delivery ofrequests from client application 110 to server application 112, and toguarantee the delivery of corresponding responses from serverapplication 112 to client application 110.

3.0 Implementation Examples

3.1 Multi-Blade Architecture

According to one embodiment, an Application-Oriented Network Services(AONS) blade in a router performs the actions discussed above. FIG. 6 isa block diagram that illustrates one embodiment of a router 600 in whicha supervisor blade 602 directs some of packet flows 610A-B to an AONSblade and/or other blades 606N. Router 600 comprises supervisor blade602, AONS blade 604, and other blades 606A-N. Each of blades 602, 604,and 606A-N is a single circuit board populated with components such asprocessors, memory, and network connections that are usually found onmultiple boards. Blades 602, 604, and 606A-N are designed to be addableto and removable from router 600. The functionality of router 600 isdetermined by the functionality of the blades therein. Adding blades torouter 600 can augment the functionality of router 600, but router 600can provide a lesser degree of functionality with fewer blades at alesser cost if desired. One of more of the blades may be optional.

Router 600 receives packet flows such as packet flows 610A-B. Morespecifically, packet flows 610A-B received by router 600 are received bysupervisor blade 602. Supervisor blade 602 may comprise a forwardingengine and/or a route processor such as those commercially availablefrom Cisco Systems, Inc.

In one embodiment, supervisor blade 602 classifies packet flows 610A-Bbased on one or more parameters contained in the packet headers of thosepacket flows. If the parameters contained in the packet header of aparticular packet match specified parameters, then supervisor blade 602sends the packets to a specified one of AONS blade 604 and/or otherblades 606A-N. Alternatively, if the parameters contained in the packetheader do not match any specified parameters, then supervisor blade 602performs routing functions relative to the particular packet andforwards the particular packet on toward the particular packet'sdestination.

For example, supervisor blade 602 may determine that packet headers inpacket flow 610B match specified parameters. Consequently, supervisorblade 602 may send packets in packet flow 610B to AONS blade 604.Supervisor blade 602 may receive packets back from AONS blade 604 and/orother blades 606A-N and send the packets on to the next hop in a networkpath that leads to those packets' destination. For another example,supervisor blade 602 may determine that packet headers in packet flow610A do not match any specified parameters. Consequently, withoutsending any packets in packet flow 610A to AONS blade 604 or otherblades 606A-N, supervisor blade 602 may send packets in packet flow 610Aon to the next hop in a network path that leads to those packets'destination.

AONS blade 604 and other blades 606A-N receive packets from supervisorblade 602, perform operations relative to the packets, and return thepackets to supervisor blade 602. Supervisor blade 602 may send packetsto and receive packets from multiple blades before sending those packetsout of router 600. For example, supervisor blade 602 may send aparticular group of packets to other blade 606A. Other blade 606A mayperform firewall functions relative to the packets and send the packetsback to supervisor blade 602. Supervisor blade 602 may receive thepacket from other blade 606A and send the packets to AONS blade 604.AONS blade 604 may perform one or more message payload-based operationsrelative to the packets and send the packets back to supervisor blade602.

According to one embodiment, the following events occur at an AONSrouter such as router 600. First, packets, containing messages fromclients to servers, are received. Next, access control list-basedfiltering is performed on the packets and some of the packets are sentto an AONS blade or module. Next, TCP termination is performed on thepackets. Next, Secure Sockets Layer (SSL) termination is performed onthe packets if necessary. Next, Universal Resource Locator (URL)-basedfiltering is performed on the packets. Next, message header-based andmessage content-based filtering is performed on the packets. Next, themessages contained in the packets are classified into AONS messagetypes. Next, a policy flow that corresponds to the AONS message type isselected. Next, the selected policy flow is executed. Then the packetsare either forwarded, redirected, dropped, copied, or fanned-out asspecified by the selected policy flow.

3.2 Message Classification

FIGS. 3A-B depict a flow diagram 300 that illustrates one embodiment ofa method of classifying application layer messages into messageclassifications and performing actions that are associated with thosemessage classifications. For example, one or more of network elements102 and 106 may perform such a method. More specifically, AONS blade 604may perform one or more steps of such a method. Other embodiments mayomit one or more of the operations depicted in flow diagram 300. Otherembodiments may contain operations additional to the operation depictedin flow diagram 300. Other embodiments may perform the operationsdepicted in flow diagram 300 in an order that differs from the orderdepicted in flow diagram 300.

Referring first to FIG. 3A, in block 302, user-specified input isreceived at a network element. The user-specified input indicates thefollowing: one or more criteria that are to be associated with aparticular message classification, and one or more actions that are tobe associated with the particular message classification. Theuser-specified input may indicate an order in which the one or moreactions are to be performed. The user-specified input may indicate thatoutputs of actions are to be supplied as inputs to other actions. Forexample, network element 102, and more specifically AONS blade 604, mayreceive such user-specified input from a network administrator.

In block 304, an association is established, at the network element,between the particular message classification and the one or morecriteria. For example, AONS blade 604 may establish an associationbetween a particular message classification and one or more criteria.For example, the criteria may indicate a particular string of text thata message needs to contain in order for the message to belong to theassociated message classification. For another example, the criteria mayindicate a particular path that needs to exist in the hierarchicalstructure of an XML-formatted message in order for the message to belongto the associated message classification. For another example, thecriteria may indicate one or more source IP addresses and/or destinationIP addresses from or to which a message needs to be addressed in orderfor the message to belong to the associated message classification.

In block 306, an association is established, at the network element,between the particular message classification and the one or moreactions. One or more actions that are associated with a particularmessage classification comprise a “policy” that is associated with thatparticular message classification. A policy may comprise a “flow” of oneor more actions that are ordered according to a particular orderspecified in the user-specified input, and/or one or more other actionsthat are not ordered. For example, AONS blade 604 may establish anassociation between a particular message classification and one or moreactions. Collectively, the operations of blocks 302-306 comprise“provisioning” the network element.

In block 308, one or more data packets that are destined for a deviceother than the network element are intercepted by the network element.The data packets may be, for example, data packets that contain IP andTCP headers. The IP addresses indicated in the IP headers of the datapackets differ from the network element's IP address; thus, the datapackets are destined for a device other than the network element. Forexample, network element 102, and more specifically, supervisor blade602, may intercept data packets that client application 110 originallysent. The data packets might be destined for server application 112, forexample.

In block 310, based on one or more information items indicated in theheaders of the data packets, an application layer protocol that was usedto transmit a message contained in the payload portions of the datapackets (hereinafter “the message”) is determined. The information itemsmay include, for example, a source IP address in an IP header, adestination IP address in an IP header, a TCP source port in a TCPheader, and a TCP destination port in a TCP header. For example, networkelement 102, and more specifically AONS blade 604, may store mappinginformation that maps FTP (an application layer protocol) to a firstcombination of IP addresses and/or TCP ports, and that maps HTTP(another application layer protocol) to a second combination of IPaddresses and/or TCP ports. Based on this mapping information and the IPaddresses and/or TCP ports indicated by the intercepted data packets,AONS blade 604 may determine which application layer protocol (FTP,HTTP, Simple Mail Transfer Protocol (SMTP), etc.) was used to transmitthe message.

In block 312, a message termination technique that is associated withthe application layer protocol used to transmit the message isdetermined. For example, AONS blade 604 may store mapping informationthat maps FTP to a first procedure, that maps HTTP to a secondprocedure, and that maps SMTP to a third procedure. The first proceduremay employ a first message termination technique that can be used toextract, from the data packets, a message that was transmitted usingFTP. The second procedure may employ a second message terminationtechnique that can be used to extract, from the data packets, a messagethat was transmitted using HTTP. The third procedure may employ a thirdmessage termination technique that can be used to extract, from the datapackets, a message that was transmitted using SMTP. Based on thismapping information and the application layer protocol used to transmitthe message, AONS blade 604 may determine which procedure should becalled to extract the message from the data packets.

In block 314, the contents of the message are determined based on thetermination technique that is associated with the application layerprotocol that was used to transmit the message. For example, AONS blade604 may provide the data packets as input to a procedure that is mappedto the application layer protocol determined in block 312. The proceduremay use the appropriate message termination technique to extract thecontents of the message from the data packets. The procedure may returnthe message as output to AONS blade 604. Thus, in one embodiment, themessage extracted from the data packets is independent of theapplication layer protocol that was used to transmit the message.

In block 316, a message classification that is associated with criteriathat the message satisfies is determined. For example, AONS blade 604may store mapping information that maps different criteria to differentmessage classifications. The mapping information indicates, amongpossibly many different associations, the association established inblock 304. AONS blade 604 may determine whether the contents of themessage satisfy criteria associated with any of the known messageclassifications. In one embodiment, if the contents of the messagesatisfy the criteria associated with a particular messageclassification, then it is determined that the message belongs to theparticular message classification.

Although, in one embodiment, the contents of the message are used todetermine a message's classification, in alternative embodiments,information beyond that contained in the message may be used todetermine the message's classification. For example, in one embodiment,a combination of the contents of the message and one or more IPaddresses and/or TCP ports indicated in the data packets that containthe message is used to determine the message's classification. Foranother example, in one embodiment, one or more IP addresses and/or TCPports indicated in the data packets that contain the message are used todetermine the message's classification, regardless of the contents ofthe message.

In block 318, one or more actions that are associated with the messageclassification determined in block 316 are performed. If two or more ofthe actions are associated with a specified order of performance, asindicated by the user-specified input, then those actions are performedin the specified order. If the output of any of the actions is supposedto be provided as input to any of the actions, as indicated by theuser-specified input, then the output of the specified action isprovided as input to the other specified action.

A variety of different actions may be performed relative to the message.For example, an action might indicate that a message is to be reliablydelivered. In this case, a unique message identifier may be insertedinto the body of the message before the message is forwarded out of thenetwork element.

For another example, an action might indicate that the message is to bedropped. In this case, the message is prevented from being forwarded outof the network element toward that message's destination. For anotherexample, an action might indicate that a message is to be compressedusing a specified compression technique before being forwarded out ofthe network element.

For another example, an action might indicate that the content of themessage is to be altered in a specified manner. For example, an actionmight indicate that specified text is to be inserted into a specifiedlocation in the message. Such a location might be specified by a path inan XML hierarchical structure of the message, for example, or by aspecified string of text occurring in the message. For another example,an action might indicate that specified text is to be deleted from themessage. For another example, an action might indicate that specifiedtext is to be substituted for other specified text in the message. Textinserted into the message might be obtained dynamically (“on the fly”)from a database that is external to the network element.

For another example, an action might indicate that the message format ofa message is to be altered in a specified manner. For example, an actionmight indicate that a message's format is to be changed from XML to someother format such as EDI. For another example, an action might indicatethat a message's format is to be changed from some format other than XMLinto XML. The message format may be altered without altering the corecontent of the message, which is independent of the message format.

For another example, an action might indicate that the message is to beforwarded using a specified application layer protocol other than theapplication layer protocol that the message's origin used to transmitthe message. For example, client application 110 might have used a firstapplication layer protocol, such as HTTP, to transmit the message. Thus,when intercepted by network element 102, the message might havecontained an HTTP header. However, in accordance with a specifiedaction, before network element 102 forwards the message towards themessage's destination, network element 102, and more specifically AONSblade 604, may modify the message so that the message will be carriedusing an application layer protocol other than HTTP (such as FTP, SMTP,etc.).

For another example, an action might indicate that the message'sdestination is to be altered so that the message will be forwardedtowards a device that is different from the device that the message'ssource originally specified. For example, in accordance with a specifiedaction, network element 102, and more specifically AONS blade 604, mightencapsulate the message in one or more new IP data packets that indicatea new destination IP address that differs from the destination IPaddress that the originally intercepted IP data packets indicated.Network element 102 may then forward the new IP data packets toward thenew destination. In this manner, message content-based routing may beachieved.

For another example, an action might indicate that a specified event isto be written into a specified log that might be external to the networkelement. For example, in accordance with a specified action, networkelement 102, and more specifically AONS blade 604, might write at leasta portion of the message, along with the IP address from which themessage was received, to a log file.

For another example, an action might indicate that the message is to beencrypted using a specified key before being forwarded to a destination.For example, in accordance with a specified action, network element 102,and more specifically AONS blade 604, might encrypt at least a portionof the message using a specified key and then forward data packets thatcontain the encrypted message towards the message's destination.

For another example, an action might indicate that a response cached atthe network element is to be returned to the device from which themessage originated, if such a response is cached at the network element.For example, network element 102, and more specifically AONS blade 604,may determine whether a response to the message is cached at networkelement 102; such a response might have be cached at network element 102at the time a previous response to the same message passed throughnetwork element 102. If network element 102 determines that such aresponse is cached, then network element 102 may return the response tothe message's origin. Consequently, network element 102 does not need toforward the message to the message's destination, and the message'sdestination does not need to issue another response to the message.

If the message was modified in some way (e.g., content, format, orprotocol modification) during the performance of the actions, and if themodified message is supposed to be forwarded out of the network element,then the network element encapsulates the modified message into new datapackets and sends the new data packets towards the modified message'sdestination—which also might have been modified.

A message might not belong to any known message classification. In thiscase, according to one embodiment, the network element does not performany user-specified actions relative to the message. Instead, the networkelement simply forwards the data packets to the next hop along the pathto the data packets' indicated destination.

As a result of the method illustrated in flow diagram 300, applicationssuch as client application 110 and server application 112 cancommunicate with each other reliably and as though no network elementsacted as intermediaries, and as though each other applicationcommunicated using the same message format and application layerprotocol.

3.3 Action Flows

FIG. 4 depicts a sample flow 400 that might be associated with aparticular message classification. Flow 400 comprises, in order, actions402-414; other flows may comprise one or more other actions. Action 402indicates that the content of the message should be modified in aspecified manner. Action 404 indicates that a specified event should bewritten to a specified log. Action 406 indicates that the message'sdestination should be changed to a specified destination. Action 408indicates that the message's format should be translated into aspecified message format. Action 410 indicates that the applicationlayer protocol used to transmit the message should be changed to aspecified application layer protocol. Action 412 indicates that themessage should be encrypted using a particular key. Action 414 indicatesthat the message should be forwarded towards the message's destination.

In other embodiments, any one of actions 402-414 may be performedindividually or in combination with any others of actions 402-414.

3.4 AONS Examples

3.4.1 AONS General Overview

Application-Oriented Network Systems (AONS) is a technology foundationfor building a class of products that embed intelligence into thenetwork to better meet the needs of application deployment. AONScomplements existing networking technologies by providing a greaterdegree of awareness of what information is flowing within the networkand helping customers to integrate disparate applications by routinginformation to the appropriate destination, in the format expected bythat destination; enforce policies for information access and exchange;optimize the flow of application traffic, both in terms of networkbandwidth and processing overheads; provide increased manageability ofinformation flow, including monitoring and metering of information flowfor both business and infrastructure purposes; and provide enhancedbusiness continuity by transparently backing up or re-routing criticalbusiness data.

AONS provides this enhanced support by understanding more about thecontent and context of information flow. As such, AONS works primarilyat the message rather than at the packet level. Typically, AONSprocessing of information terminates a TCP connection to inspect thefull message, including the “payload” as well as all headers. AONS alsounderstands and assists with popular application-level protocols such asHTTP, FTP, SMTP and de facto standard middleware protocols.

AONS differs from middleware products running on general-purposecomputing systems in that AONS' behavior is more akin to a networkappliance, in its simplicity, total cost of ownership and performance.Furthermore, AONS integrates with network-layer support to provide amore holistic approach to information flow and management, mappingrequired features at the application layer into low-level networkingfeatures implemented by routers, switches, firewalls and othernetworking systems.

Although some elements of AONS-like functionality are provided inexisting product lines from Cisco Systems, Inc., such products typicallywork off a more limited awareness of information, such as IP/portaddresses or HTTP headers, to provide load balancing and failoversolutions. AONS provides a framework for broader functional support, abroader class of applications and a greater degree of control andmanagement of application data.

3.4.2 AONS Terminology

An “application” is a software entity that performs a business functioneither running on servers or desktop systems. The application could be apackaged application, software running on application servers, a legacyapplication running on a mainframe, or custom or proprietary softwaredeveloped in house to satisfy a business need or a script that performssome operation. These applications can communicate with otherapplications in the same department (departmental), across departmentswithin a single enterprise (intra enterprise), across an enterprise andits partners (inter-enterprise or B2B) or an enterprise and itscustomers (consumers or B2C). AONS provides value added services for anyof the above scenarios.

An “application message” is a message that is generated by anapplication to communicate with another application. The applicationmessage could specify the different business level steps that should beperformed in handling this message and could be in any of the messageformats described in the section below. In the rest of the document,unless otherwise specified explicitly, the term “message” also refers toan application message.

An “AONS node” is the primary AONS component within the AONS system (ornetwork). As described later, the AONS node can take the shape of aclient proxy, server proxy or an intermediate device that routesapplication messages.

Each application message, when received by the first AONS node, getsassigned an AONS message ID and is considered to be an “AONS message”until that message gets delivered to the destination AONS node. Theconcept of the AONS message exists within the AONS cloud. A singleapplication message may map to more than one AONS message. This may bethe case, for example, if the application message requires processing bymore than one business function. For example, a “LoanRequest” messagethat is submitted by a requesting application and that needs to beprocessed by both a “CreditCheck” application and a “LoanProcessing”application would require processing by more than one business function.In this example, from the perspective of AONS, there are two AONSmessages: The “LoanRequest” to the “CreditCheck” AONS message from therequesting application to the CreditCheck application; and the“LoanRequest” to the “LoanProcessing” AONS message from the CreditCheckapplication to the LoanProcessing Application.

In one embodiment, AONS messages are encapsulated in an AONP (AONProtocol) header and are translated to a “canonical” format.Reliability, logging and security services are provided from an AONSmessage perspective.

The set of protocols or methods that applications typically use tocommunicate with each other are called “application access protocols”(or methods) from an AONS perspective. Applications can communicate tothe AONS network (typically end point proxies: a client proxy and aserver proxy) using any supported application access methods. Someexamples of application access protocols include: IBM MQ Series, JavaMessage Service (JMS), TIBCO, Simple Object Access Protocol (SOAP) overHypertext Transfer Protocol (HTTP)/HTTPS, and Simple Mail TransferProtocol (SMTP). Details about various access methods are explained inlater sections of this document.

There are a wide variety of “message formats” that are used byapplications. These message formats may range from custom or proprietaryformats to industry-specific formats to standardized formats. ExtensibleMarkup Language (XML) is gaining popularity as a universal language ormessage format for applications to communicate with each other. AONSsupports a wide variety of these formats.

In addition, AONS provides translation services from one format toanother based on the needs of applications. A typical deployment mightinvolve a first AONS node that receives an application message (theclient proxy) translating the message to a “canonical” format, which iscarried as an AONS message through the AONS network. The server proxymight translate the message from the “canonical” format to the formatunderstood by the receiving application before delivering the message.For understanding some of the non-industry standard formats, a messagedictionary may be used.

A node that performs the gateway functionality between multipleapplication access methods or protocols is called a “protocol gateway.”An example of this would be a node that receives an application messagethrough File Transfer Protocol (FTP) and sends the same message toanother application as a HTTP post. In AONS, the client and serverproxies are typically expected to perform the protocol gatewayfunctionality.

If an application generates a message in Electronic Data Interchange(EDI) format and if the receiving application expects the message to bein an XML format, then the message format needs to be translated but thecontent of the message needs to be kept intact through the translation.In AONS, the end point proxies typically perform this “message formattranslation” functionality.

In some cases, even though the sending and receiving application use thesame message format, the content needs to be translated for thereceiving application. For example, if a United States-residentapplication is communicating with a United Kingdom-resident application,then the date format in the messages between the two applications mightneed to be translated (from mm/dd/yyyy to dd/mm/yyyy) even if theapplications use the same data representation (or message format). Thistranslation is called “content translation.”

3.4.3 AONS Functional Overview

As defined previously, AONS can be defined as network based intelligentintermediary systems that efficiently and efficiently integrate businessand application needs with more flexible and responsive networkservices.

In particular, AONS can be understood through the followingcharacteristics:

AONS operates at a higher layer (layers 5-6) than traditional networkelement products (layers 2-4). AONS uses message-level inspection as acomplement to packet-level inspection—by understanding applicationmessages, AONS adds value to multiple network element products, such asswitches, firewalls, content caching systems and load balancers, on the“message exchange route.” AONS provides increased flexibility andgranularity of network responsiveness in terms of security, reliability,traffic optimization (compression, caching), visibility (business eventsand network events) and transformation (e.g., from XML to EDI).

AONS is a comprehensive technology platform, not just a point solution.AONS can be implemented through distributed intelligent intermediarysystems that sit between applications, middleware, and databases in adistributed intra- and inter-enterprise environment (routing messages,performing transformations, etc.). AONS provides a flexible frameworkfor end user configuration of business flows and policies andpartner-driven extensibility of AONS services.

AONS is especially well suited for network-based deployment. AONS isnetwork-based rather than general-purpose server-based. AONS is hybridsoftware-based and hardware-based (i.e., application-specific integratedcircuit (ASIC)/field programmable gate array (FPGA)-based acceleration).AONS uses out-of-band or in-line processing of traffic, as determined bypolicy. AONS is deployed in standalone products (network appliances) aswell as embedded products (service blades for multiple switching,routing, and storage platforms).

3.4.4 AONS System Overview

This section outlines the system overview of an example AONS system.FIG. 7 is a diagram 700 that illustrates the various components involvedin an example AONS network 702 according to one embodiment of theinvention. The roles performed by each of the nodes are mentioned indetail in subsequent sections.

Within AONS network 702, key building blocks include AONS EndpointProxies (AEPs) 704-710 and an AONS Router (AR). Visibility intoapplication intent may begin within AEP 704 placed at the edge of alogical AONS “cloud.” As a particular client application of clientapplications 714A-N attempts to send a message across the network to aparticular server application destination of server applications 716A-Nand 718A-N, the particular client application will first interact withAEP 704.

AEP 704 serves as either a transparent or explicit messaging gatewaywhich aggregates network packets into application messages and infersthe message-level intent by examining the header and payload of a givenmessage, relating the message to the appropriate context, optionallyapplying appropriate policies (e.g. message encryption, transformation,etc.) and then routing the message towards the message's applicationdestination via a network switch.

AONS Router (AR) 712 may intercept the message en route to the message'sdestination endpoint. Based upon message header contents, AR 712 maydetermine that a new route would better serve the needs of a givenapplication system. AR 712 may make this determination based uponenterprise-level policy, taking into account current network conditions.As the message nears its destination, the message may encounter AEP 706,which may perform a final set of operations (e.g. message decryption,acknowledgement of delivery) prior to the message's arrival. In oneembodiment, each message is only parsed once: when the message firstenters the AONS cloud. It is the first AEP that a message traverses thatis responsible for preparing a message for optimal handling within theunderlying network.

AEPs 704-708 can further be classified into AEP Client Proxies and AEPServer Proxies to explicitly highlight roles and operations performed bythe AEP on behalf of the specific end point applications.

A typical message flow involves a particular client application 714Asubmitting a message to the AEP Client Proxy (CP) 704 through one of thevarious access protocols supported by AONS. On receiving this message,AEP CP 704 assigns an AONS message id to the message, encapsulates themessage with an AONP header, and performs any necessary operationsrelated to the AONS network (e.g. security and reliability services).Also, if necessary, the message is converted to a “canonical” format byAEP CP 704. The message is carried over a TCP connection to AR 710 alongthe path to the destination application 718A. The AONS routers along thepath perform the infrastructure services necessary for the message andcan change the routing based on the policies configured by the customer.The message is received at the destination AEP Server Proxy (SP) 706.AEP SP 706 performs necessary security and reliability functions andtranslates the message to the format that is understood by the receivingapplication, if necessary. AEP SP 706 then sends the message toreceiving application 718A using any of the access protocols thatapplication 718A and AONS support. A detailed message flow through AONSnetwork 702 is described in later sections.

3.4.5 AONS System Elements

This section outlines the different concepts that are used from an AONSperspective.

An “AEP Client Proxy” is an AONS node that performs the servicesnecessary for applications on the sending side of a message (a client).In the rest of this document, an endpoint proxy also refers to a clientor server proxy. The typical responsibilities of the client proxy inprocessing a message are: message pre-classification & early rejection,protocol management, message identity management, message encapsulationin an AONP header, end point origination for reliable delivery, securityend point service origination (encryption, digital signature,authentication), flow selection & execution/infrastructure services(logging, compression, content transformation, etc.), routing—next hopAONS node or destination, AONS node and route discovery/advertising roleand routes, and end point origination for the reliable deliverymechanism (guaranteed delivery router).

Not all functionalities described above need to be performed for eachmessage. The functionalities performed on the message are controlled bythe policies configured for the AONS node.

An “AEP Server Proxy” is an AONS node that performs the servicesnecessary for applications on the receiving side of a message (aserver). In the rest of the document, a Server Proxy may also bereferred as an end point proxy. The typical responsibilities of theServer Proxy in processing a message are: protocol management, end pointtermination for reliable delivery, security end point servicetermination (decryption, verification of digital signature, etc.), flowselection & execution/infrastructure services (logging, compression,content translation, etc.), message de-encapsulation in AONP header,acknowledgement to sending AONS node, application routing/requestmessage delivery to destination, response message correlation, androuting to entry AONS node.

Note that not all the functionalities listed above need to be performedfor each message. The functionalities performed on the message arecontrolled by the policies configured for the AONS node and what themessage header indicates.

An “AONS Router” is an AONS node that provides message-forwardingfunctionalities along with additional infrastructure services within anAONS network. An AONS Router communicates with Client Proxies, ServerProxies and other AONS Routers. An AONS Router may provide servicewithout parsing a message; an AONS Router may rely on an AONP messageheader and the policies configured in the AONS network instead ofparsing messages. An AONS Router provides the following functionalities:scalability in the AONS network in terms of the number of TCPconnections needed; message routing based on message destination,policies configured in the AONS cloud, a route specified in the message,and/or content of the message; a load at the intendeddestination-re-routing if needed; availability of thedestination—re-routing if needed; cost of transmission (selection amongmultiple service providers); and infrastructure services such as sendingto a logging facility, sending to a storage area network (SAN) forbackup purposes, and interfacing to a cache engine for cacheablemessages (like catalogs).

AONS Routers do not need to understand any of the application accessprotocols and, in one embodiment, deal only with messages encapsulatedwith an AONP header.

Application-Oriented Networking Protocol (AONP) is a protocol used forcommunication between the nodes in an AONS network. In one embodiment,each AONS message carries an AONP header that conveys the destination ofthe message and additional information for processing the message insubsequent nodes. AONP also addresses policy exchange (static ordynamic), fail-over among nodes, load balancing among AONS nodes, andexchange of routing information. AONP also enables application-orientedmessage processing in multiple network elements (like firewalls, cacheengines and routers/switches). AONP supports both a fixed header and avariable header (formed using type-length-value (TLV) fields) to supportefficient processing in intermediate nodes as well as flexibility foradditional services.

Unless explicitly specified otherwise, “router” or “switch” refersherein to a typical Layer 3 or Layer 2 switch or a router that iscurrently commercially available.

3.4.6 AONS Example Features

In one embodiment, an underlying “AONS foundation platform of subsystemservices” (AOS) provides a range of general-purpose services includingsupport for security, compression, caching, reliability, policymanagement and other services. On top of this platform, AONS then offersa range of discreet functional components that can be wired together toprovide the overall processing of incoming data traffic. These“bladelets™” are targeted at effecting individual services in thecontext of the specific policy or action demanded by the application orthe information technology (IT) manager. A series of access methodadaptors ensure support for a range of ingress and egress formats.Finally, a set of user-oriented tools enable managers to appropriatelyview, configure and set policies for the AONS solution. These fourcategories of functions combine to provide a range of end-customercapabilities including enhanced security, infrastructure optimization,business continuity, application integration and operational visibility.

The enhanced visibility and enhanced responsiveness enabled by AONSsolutions provides a number of intelligent, application-oriented networkservices. These intelligent services can be summarized in four primarycategories:

Enhanced security and reliability: enabling reliable message deliveryand providing message-level security in addition to existingnetwork-level security.

Infrastructure optimization: making more efficient use of networkresources by taking advantage of caching and compression at the messagelevel as well as by integrating application and networkquality-of-service (QoS).

Business and infrastructure activity monitoring and management: byreading information contained in the application layer message, AONS canlog, audit, and manage application-level business events, and combinethese with network, server, and storage infrastructure events in acommon, policy-driven management environment.

Content-based routing and transformation: message-based routing andtransformation of protocol, content, data, and message formats (e.g.,XML transformation). The individual features belonging to each of theseprimary categories are described in greater detail below.

3.4.6.1 Enhanced Security and Reliability

Authentication: AONS can verify the identity of the sender of an inboundmessage based upon various pieces of information contained within agiven message (username/password, digital certificate, SecurityAssertion Markup Language (SAML) assertion, etc.), and, based upon thesecredentials, determine whether or not the message should be processedfurther.

Authorization: Once principal credentials are obtained via messageinspection, AONS can determine what level of access the originator ofthe message should have to the services it is attempting to invoke. AONSmay also make routing decisions based upon such derived privileges orblock or mask certain data elements within a message once it's within anAONS network as appropriate.

Encryption/Decryption: Based upon policy, AONS can perform encryption ofmessage elements (an entire message, the message body or individualelements such as credit card number) to maintain end-to-endconfidentiality as a message travels through the AONS network.Conversely, AONS can perform decryption of these elements prior toarrival at a given endpoint.

Digital Signatures: In order to ensure message integrity and allow fornon-repudiation of message transactions, AONS can digitally sign entiremessages or individual message elements at any given AEP. The decisionas to what gets signed will be determined by policy as applied toinformation derived from the contents and context of each message.

Reliability: AONS can complement existing guaranteed messaging systemsby intermediating between unlike proprietary mechanisms. It can alsoprovide reliability for HTTP-based applications (including web services)that currently lack reliable delivery. As an additional feature, AONScan generate confirmations of successful message delivery as well asautomatically generate exception responses when delivery cannot beconfirmed.

3.4.6.2 Infrastructure Optimization

Compression: AEPs can compress message data prior to sending the messagedata across the network in order to conserve bandwidth and converselydecompress it prior to endpoint delivery.

Caching: AONS can cache the results of previous message inquires basedupon the rules defined for a type of request or based upon indicatorsset in the response. Caching can be performed for entire messages or forcertain elements of a message in order to reduce application responsetime and conserve network bandwidth utilization. Message element cachingenables delta processing for subsequent message requests.

TCP Connection Pooling: By serving as an intermediary between messageclients and servers AONS can consolidate the total number of persistentconnections required between applications. AONS thereby reduces theclient and server-processing load otherwise associated with the ongoinginitiation and teardown of connections between a mesh of endpoints.

Batching: An AONS intermediary can batch transactional messages destinedfor multiple destinations to reduce disk I/O overheads on the sendingsystem. Similarly, transactional messages from multiple sources can bebatched to reduce disk I/O overheads on the receiving system.

Hardware Acceleration: By efficiently performing compute-intensivefunctions such as encryption and Extensible Stylesheet LanguageTransformation (XSLT) transformations in an AONS network device usingspecialized hardware, AONS can offload the computing resources ofendpoint servers, providing potentially lower-cost processingcapability.

Quality of Service: AONS can integrate application-level QoS withnetwork-level QoS features based on either explicit messageprioritization (e.g., a message tagged as “high priority”) or via policythat determines when a higher quality of network service is required fora message as specific message content is detected.

Policy Enforcement: At the heart of optimizing the overall AONS solutionis the ability to ensure business-level polices are expressed,implemented and enforced by the infrastructure. The AONS Policy Managerensures that once messages are inspected, the appropriate actions(encryption, compression, routing, etc.) are taken against that messageas appropriate.

3.4.6.3 Activity Monitoring and Management

Auditing/Logging/Metering: AONS can selectively filter messages and sendthem to a node or console for aggregation and subsequent analysis. Toolsenable viewing and analysis of message traffic. AONS can also generateautomatic responses to significant real-time events, both business andinfrastructure-related. By intelligently gathering statistics andsending them to be logged, AONS can produce metering data for auditingor billing purposes.

Management: AONS can combine both message-level and networkinfrastructure level events to gain a deeper understanding of overallsystem health. The AONS management interface itself is available as aweb service for those who wish to access it programmatically.

Testing and Validation: AONS' ability to intercept message traffic canbe used to validate messages before allowing them to reach destinationapplications. In addition to protecting from possible application orserver failures, this capability can be leveraged to test new webservices and other functions by examining actual message flow fromclients and servers prior to production deployment. AONS also provides a“debug mode” that can be turned on automatically after a suspectedfailure or manually after a notification to assist with the overallmanagement of the device.

Workload Balancing and Failover: AONS provides an approach to workloadbalancing and failover that is both policy- and content-driven. Forexample, given an AONS node's capability to intermediate betweenheterogeneous systems, the AONS node can balance between unlike systemsthat provide access to common information as requested by the contentsof a message. AONS can also address the issue of message affinitynecessary to ensure failover at the message rather than just the sessionlevel as is done by most existing solutions. Balancing can also takeinto account the response time for getting a message reply, routing toan alternate destination if the preferred target is temporarily slow torespond.

Business Continuity: By providing the ability to replicate inboundmessages to a remote destination, AONS enables customers to quicklyrecover from system outages. AONS can also detect failed messagedelivery and automatically re-route to alternate endpoints. AONS AEPsand ARs themselves have built-in redundancy and failover at thecomponent level and can be clustered to ensure high availability.

3.4.6.4 Content-Based Routing and Transformation

Content-based Routing: Based upon its ability to inspect and understandthe content and context of a message, AONS provides the capability toroute messages to an appropriate destination by matching contentelements against pre-established policy configurations. This capabilityallows AONS to provide a common interface (service virtualization) formessages handled by different applications, with AONS examining messagetype or fields in the content (part number, account type, employeelocation, customer zip code, etc.) to route the message to theappropriate application. This capability also allows AONS to send amessage to multiple destinations (based on either statically defined ordynamic subscriptions to message types or information topics), withoptimal fan-out through AONS routers. This capability further allowsAONS to redirect all messages previously sent to an application so thatit can be processed by a new application. This capability additionallyallows AONS to route a message for a pre-processing step that is deemedto be required before receipt of a message (for example, introducing amanagement pre-approval step for all travel requests). Thus capabilityalso allows AONS to route a copy of a message that exceeds certaincriteria (e.g. value of order) to an auditing system, as well asforwarding the message to the intended destination. This capabilityfurther allows AONS to route a message to a particular server forworkload or failover reasons. This capability also allows AONS to routea message to a particular server based on previous routing decisions(e.g., routing a query request based on which server handled for theoriginal order). This capability additionally allows AONS to route basedon the source of a message. This capability also allows AONS to route amessage through a sequence of steps defined by a source or previousintermediary.

Message Protocol Gateway: AONS can act as a gateway between applicationsusing different transport protocols. AONS supports open standardprotocols (e.g. HTTP, FTP, SMTP), as well as popular or de factostandard proprietary protocols such as IBM Websphere MQ.

Message Transformations: AONS can transform the contents of a message tomake them appropriate for a particular receiving application. This canbe done for both XML and non-XML messages, the latter via the assistanceof either a message dictionary definition or a well-defined industrystandard format.

3.4.7 AONS Functional Modules

FIG. 8 is a block diagram that depicts functional modules within anexample AONS node. AONS node 800 comprises AOS configuration andmanagement module 802, flows/rules 804, AOS common services 806, AOSmessage execution controller 808, AOS protocol access methods 810, andAOS platform-specific “glue” 812. AONS node 800 interfaces withInternetworking Operating System (IOS) 814 and Linux Operating System816. Flows/rules 804 comprise bladelets™ 818, scriptlets™ 820, andscriptlet™ container 822.

In one embodiment, AOS common services 806 include: security services,standard compression services, delta compression services, cachingservice, message logging service, policy management service, reliablemessaging service, publish/subscribe service, activity monitoringservice, message distribution service, XML parsing service, XSLTtransformation service, and QoS management service.

In one embodiment, AOS protocol/access methods 810 include: TCP/SSL,HTTP/HTTPS, SOAP/HTTP, SMTP, FTP, JMS/MQ and JMS/RV, and Java DatabaseConnectivity (JDBC).

In one embodiment, AOS message execution controller 808 includes: anexecution controller, a flow subsystem, and a bladelet™ subsystem.

In one embodiment, AOS bladelets™ 818 and scriptlets™ 820 include:message input (read message), message output (send message),logging/audit, decision, external data access, XML parsing, XMLtransformation, caching, scriptlet container, publish, subscribe,message validation (schema, format, etc.), filtering/masking, signing,authentication, authorization, encryption, decryption, activitymonitoring sourcing, activity monitoring marking, activity monitoringprocessing, activity monitoring notification, message discard, firewallblock, firewall unblock, message intercept, and message stop-intercept.

In one embodiment, AOS configuration and management module 802 includes:configuration, monitoring, topology management, capability exchange,failover redundancy, reliability/availability/serviceability (RAS)services (tracing, debugging, etc.), archiving, installation, upgrades,licensing, sample scriptlets™, sample flows, documentation, online help,and language localization.

In one embodiment, supported platforms include: Cisco Catalyst 6503,Cisco Catalyst 6505, Cisco Catalyst 6509, and Cisco Catalyst 6513. Inone embodiment, supported supervisor modules include: Sup2 and Sup720.In one embodiment, specific functional areas relating to the platforminclude: optimized TCP, SSL, public key infrastructure (PKI),encryption/decryption, interface to Cat6K supervisor,failover/redundancy, image management, and QoS functionality.

3.4.8 AONS Modes of Operation

AONS may be configured to run in multiple modes depending on applicationintegration needs, and deployment scenarios. According to oneembodiment, the primary modes of operation include implicit mode,explicit mode, and proxy mode. In implicit mode, an AONS nodetransparently intercepts relevant traffic with no changes toapplications. In explicit mode, applications explicitly address trafficto an intermediary AONS node. In proxy mode, applications are configuredto work in conjunction with AONS nodes, but applications do notexplicitly address traffic to AONS nodes.

In implicit mode, applications are unaware of AONS presence. Messagesare address to receiving applications. Messages are redirected to AONSvia configuration of application “proxy” or middleware systems to routemessages to AONS, and/or via configuration of networks (packetinterception). For example, domain name server (DNS)-based redirectioncould be used to route messages. For another example, a 5-tuple-basedaccess control list (ACL) on a switch or router could be used.Network-based application recognition and content switching modules maybe configured for URL/URI redirection. Message-based inspection may beused to determine message types and classifications. In implicit mode,applications communicate with each other using AONS as an intermediary(implicitly), using application-native protocols.

Traffic redirection, message classification, and “early rejection”(sending traffic out of AONS layers prior to complete processing withinAONS layers) may be accomplished via a variety of mechanisms, such asthose depicted in FIG. 9. FIG. 9 shows multiple tiers of filtering thatmay be performed on message traffic in order to produce only a selectset of traffic that will be processed at the AONS layer. Traffic that isnot processed at the AONS layer may be treated as any other traffic.

At the lowest layer, layer 902, all traffic passes through. At the nexthighest layer, layer 904, traffic may be filtered based on 5-tuples. Asupervisor blade or Internetwork Operating System (IOS) may perform suchfiltering. Traffic that passes the filters at layer 904 passes to layer906. At layer 906, traffic may be further filtered based onnetwork-based application recognition-like filtering and/or messageclassification and rejection. Traffic that passes the filters at layer906 passes to layer 908. At layer 908, traffic may be further filteredbased on protocol headers. For example, traffic may be filtered based onURLs/URIs in the traffic. Traffic that passes the filters at layer 908passes to layer 910. At layer 910, traffic may be processed based onapplication layer messages, include headers and contents. For example,XPath paths within messages may be used to process traffic at layer 910.An AONS blade may perform processing at layer 910. Thus, a select subsetof all network traffic may be provided to an AONS blade.

In explicit mode, applications are aware of AONS presence. Messages areexplicitly addressed to AONS nodes. Applications may communicate withAONS using AONP. AONS may perform service virtualization and destinationselection.

In proxy mode, applications are explicitly unaware of AONS presence.Messages are addressed to their ultimate destinations (i.e.,applications). However, client applications are configured to directtraffic via a proxy mode.

3.4.9 AONS Message Routing

Components of message management in AONS may be viewed from twoperspectives: a node view and a cloud view.

FIG. 10 is a diagram that illustrates the path of a message within anAONS cloud 1010 according to a cloud view. A client application 1004sends a message to an AONS Client Proxy (CP) 1006. If AONS CP 1006 isnot present, then client application 1004 may send the message to anAONS Server Proxy (SP) 1008. The message is processed at AONS CP 1006.AONS CP 1006 transforms the message into AONP format if the message isentering AONS cloud 1010.

Within AONS cloud 1010, the message is routed using AONP. Thus, usingAONP, the message may be routed from AONS CP 1006 to an AONS router1012, or from AONS CP 1006 to AONS SP 1008, or from AONS router 1012 toanother AONS router, or from AONS router 1012 to AONS SP 1008. Messagesprocessed at AONS nodes are processed in AONP format.

When the message reaches AONS SP 1008, AONS SP 1008 transforms themessage into the message format used by server application 1014. AONS SP1008 routes the message to server application 1014 using the messageprotocol of server application 1014. Alternatively, if AONS SP 1008 isnot present, AONS CP 1006 may route the message to server application1014.

The details of the message processing within AONS cloud 1010 can beunderstood via the following perspectives: Request/Response MessageFlow, One-Way Message Flow, Message Flow with Reliable Delivery, andNode-to-Node Communication.

FIG. 11A and FIG. 11B are diagrams that illustrate a request/responsemessage flow. Referring to FIG. 11A, at circumscribed numeral 1, asending application 1102 sends a message towards a receiving application1104. At circumscribed numeral 2, an AEP CP 1106 intercepts the messageand adds an AONP header to the message, forming an AONP message. Atcircumscribed numeral 3, AEP CP 1106 sends the AONP message to an AONSrouter 1108. At circumscribed numeral 4, AONS router 1108 receives theAONP message. At circumscribed numeral 5, AONS router 1108 sends theAONP message to an AEP SP 1110. At circumscribed numeral 6, AEP SP 1110receives the AONP message and removes the AONP header from the message,thus decapsulating the message. At circumscribed numeral 7, AEP SP 1110sends the message to receiving application 1104.

Referring to FIG. 11B, at circumscribed numeral 8, receiving application1104 sends a response message toward sending application 1102. Atcircumscribed numeral 9, AEP SP 1110 intercepts the message and adds anAONP header to the message, forming an AONP message. At circumscribednumeral 10, AEP SP 1110 sends the AONP message to AONS router 1108. Atcircumscribed numeral 11, AONS router 1108 receives the AONP message. Atcircumscribed numeral 12, AONS router 1108 sends the AONP message to AEPCP 1106. At circumscribed numeral 13, AEP CP 1106 receives the AONPmessage and removes the AONP header from the message, thus decapsulatingthe message. At circumscribed numeral 14, AEP CP 1106 sends the messageto sending application 1102. Thus, a request is routed from sendingapplication 1102 to receiving application 1104, and a response is routedfrom receiving application 1104 to sending application 1102.

FIG. 12A and FIG. 12B are diagrams that illustrate alternativerequest/response message flows. FIG. 12A shows three possible routesthat a message might take from a sending application 1202 to a receivingapplication 1204. According to a first route, sending application 1202sends the message toward receiving application 1204, but an AEP CP 1206intercepts the message and sends the message to receiving application1204. According to a second route, sending application 1202 sends themessage toward receiving application 1204, but AEP CP 1206 interceptsthe message, encapsulates the message within an AONP message, and sendsthe AONP message to an AEP SP 1208, which decapsulates the message fromthe AONP message and sends the message to receiving application 1204.According to a third route, sending application 1202 sends the messagetoward receiving application 1204, but AEP SP 1208 intercepts themessage and sends the message to receiving application 1204.

FIG. 12B shows three possible routes that a response message might takefrom receiving application 1204 to sending application 1202. Accordingto a first route, receiving application 1204 sends the message towardsending application 1202, but AEP CP 1206 intercepts the message andsends the message to sending application 1204. According to a secondroute, receiving application 1204 sends the message toward sendingapplication 1202, but AEP SP 1208 intercepts the message, encapsulatesthe message within an AONP message, and sends the AONP message to AEP CP1206, which decapsulates the message from the AONP message and sends themessage to sending application 1202. According to a third route,receiving application 1204 sends the message toward sending application1202, but AEP SP 1208 intercepts the message and sends the message tosending application 1202.

FIG. 13 is a diagram that illustrates a one-way message flow. Atcircumscribed numeral 1, a sending application 1302 sends a messagetowards a receiving application 1304. At circumscribed numeral 2, an AEPCP 1306 intercepts the message and adds an AONP header to the message,forming an AONP message. At circumscribed numeral 3, AEP CP 1306 sendsan ACK (acknowledgement) back to sending application 1302. Atcircumscribed numeral 4, AEP CP 1306 sends the AONP message to an AONSrouter 1308. At circumscribed numeral 5, AONS router 1308 receives theAONP message. At circumscribed numeral 6, AONS router 1308 sends theAONP message to an AEP SP 1310. At circumscribed numeral 7, AEP SP 1310receives the AONP message and removes the AONP header from the message,thus decapsulating the message. At circumscribed numeral 8, AEP SP 1310sends the message to receiving application 1304.

FIG. 14 is a diagram that illustrates alternative one-way message flows.FIG. 14 shows three possible routes that a message might take from asending application 1402 to a receiving application 1404. According to afirst route, sending application 1402 sends the message toward receivingapplication 1404, but an AEP CP 1406 intercepts the message and sendsthe message to receiving application 1404. AEP CP 1406 sends an ACK(acknowledgement) to sending application 1402. According to a secondroute, sending application 1402 sends the message toward receivingapplication 1404, but AEP CP 1406 intercepts the message, encapsulatesthe message within an AONP message, and sends the AONP message to an AEPSP 1408, which decapsulates the message from the AONP message and sendsthe message to receiving application 1404. Again, AEP CP 1406 sends anACK to sending application 1402. According to a third route, sendingapplication 1402 sends the message toward receiving application 1404,but AEP SP 1408 intercepts the message and sends the message toreceiving application 1404. In this case, AEP SP 1408 sends an ACK tosending application 1402. Thus, when an AEP intercepts a message, theintercepting AEP sends an ACK to the sending application.

According to one embodiment, AONP is used in node-to-node communicationwith the next hop. In one embodiment, AONP uses HTTP. AONP headers mayinclude HTTP or TCP headers. AONP may indicate RM ACK, QoS level,message priority, and message context (connection, message sequencenumbers, message context identifier, entry node information, etc.). Theactual message payload is in the message body. Asynchronous messagingmay be used between AONS nodes. AONS may conduct route and nodediscovery via static configuration (next hop) and/or via dynamicdiscovery and route advertising (“lazy” discovery).

FIG. 15A and FIG. 15B are diagrams that illustrate a request/responsemessage flow with reliable message delivery. Referring to FIG. 15A, atcircumscribed numeral 1, a sending application 1502 sends a messagetowards a receiving application 1504. At circumscribed numeral 2, an AEPCP 1506 intercepts the message and adds an AONP header to the message,forming an AONP message. At circumscribed numeral 3, AEP CP 1506 savesthe message to a data store 1512. Thus, if there are any problems withsending the message, AEP CP 1506 can resend the copy of the message thatis stored in data store 1512.

At circumscribed numeral 4, AEP CP 1506 sends the AONP message to anAONS router 1508. At circumscribed numeral 5, AONS router 1508 receivesthe AONP message. At circumscribed numeral 6, AONS router 1508 sends theAONP message to an AEP SP 1510. At circumscribed numeral 7, AEP SP 1510receives the AONP message and removes the AONP header from the message,thus decapsulating the message. At circumscribed numeral 8, AEP SP 1510sends the message to receiving application 1504.

At circumscribed numeral 9, AEP SP 1510 sends a reliable messaging (RM)acknowledgement (ACK) to AONS router 1508. At circumscribed numeral 10,AONS router 1508 receives the RM ACK and sends the RM ACK to AEP CP1506. At circumscribed numeral 11, AEP CP 1506 receives the RM ACK and,in response, deletes the copy of the message that is stored in datastore 1512. Because the delivery of the message has been acknowledged,there is no further need to store a copy of the message in data store1512. Alternatively, if AEP CP 1506 does not receive the RM ACK within aspecified period of time, then AEP CP 1506 resends the message.

Referring to FIG. 15B, at circumscribed numeral 12, receivingapplication 1504 sends a response message toward sending application1502. At circumscribed numeral 13, AEP SP 1510 intercepts the messageand adds an AONP header to the message, forming an AONP message. Atcircumscribed numeral 14, AEP SP 1510 sends the AONP message to AONSrouter 1508. At circumscribed numeral 15, AONS router 1508 receives theAONP message. At circumscribed numeral 16, AONS router 1508 sends theAONP message to AEP CP 1506. At circumscribed numeral 17, AEP CP 1506receives the AONP message and removes the AONP header from the message,thus decapsulating the message. At circumscribed numeral 18, AEP CP 1506sends the message to sending application 1502.

FIG. 16 is a diagram that illustrates a one-way message flow withreliable message delivery. At circumscribed numeral 1, a sendingapplication 1602 sends a message towards a receiving application 1604.At circumscribed numeral 2, an AEP CP 1606 intercepts the message andadds an AONP header to the message, forming an AONP message. Atcircumscribed numeral 3, AEP CP 1606 saves the message to a data store1612. Thus, if there are any problems with sending the message, AEP CP1606 can resend the copy of the message that is stored in data store1612. At circumscribed numeral 4, AEP CP 1606 sends an ACK(acknowledgement) back to sending application 1602. At circumscribednumeral 5, AEP CP 1606 sends the AONP message to an AONS router 1608. Atcircumscribed numeral 6, AONS router 1608 receives the AONP message. Atcircumscribed numeral 7, AONS router 1608 sends the AONP message to anAEP SP 1610. At circumscribed numeral 8, AEP SP 1610 receives the AONPmessage and removes the AONP header from the message, thus decapsulatingthe message. At circumscribed numeral 9, AEP SP 1610 sends the messageto receiving application 1604.

At circumscribed numeral 10, AEP SP 1610 sends a reliable messaging (RM)acknowledgement (ACK) to AONS router 1608. At circumscribed numeral 11,AONS router 1608 receives the RM ACK and sends the RM ACK to AEP CP1606. At circumscribed numeral 12, AEP CP 1606 receives the RM ACK and,in response, deletes the copy of the message that is stored in datastore 1612. Because the delivery of the message has been acknowledged,there is no further need to store a copy of the message in data store1612. Alternatively, if AEP CP 1606 does not receive the RM ACK within aspecified period of time, then AEP CP 1606 resends the message.

FIG. 17 is a diagram that illustrates synchronous request and responsemessages. At circumscribed numeral 1, an AONS node 1704 receives, from aclient 1702, a request message, in either implicit or explicit mode. Atcircumscribed numeral 2, AONS node 1704 reads the message, selects andexecutes a flow, and adds an AONP header to the message. Atcircumscribed numeral 3, AONS node 1704 sends the message to a next hopnode, AONS node 1706. At circumscribed numeral 4, AONS node 1706 readsthe message, selects and executes a flow, and removes the AONP headerfrom the message, formatting the message according to the message formatexpected by a server 1708. At circumscribed numeral 5, AONS node 1706sends the message to the message's destination, server 1708.

At circumscribed numeral 6, AONS node 1706 receives a response messagefrom server 1708 on the same connection on which AONS node 1706 sent therequest message. At circumscribed numeral 7, AONS node 1706 reads themessage, correlates the message with the request message, executes aflow, and adds an AONP header to the message. At circumscribed numeral8, AONS node 1706 sends the message to AONS node 1704. At circumscribednumeral 9, AONS node 1704 reads the message, correlates the message withthe request message, executes a flow, and removes the AONP header fromthe message, formatting the message according to the message formatexpected by client 1702. At circumscribed numeral 10, AONS node 1704sends the message to client 1702 on the same connection on which client1702 sent the request message to AONS node 1704.

FIG. 18 is a diagram that illustrates a sample one-way end-to-endmessage flow. At circumscribed numeral 1, an AONS node 1804 receives,from a client 1802, a request message, in either implicit or explicitmode. At circumscribed numeral 2, AONS node 1804 reads the message,selects and executes a flow, and adds an AONP header to the message. Atcircumscribed numeral 3, AONS node 1804 sends an acknowledgement toclient 1802. At circumscribed numeral 4, AONS node 1804 sends themessage to a next hop node, AONS node 1806. At circumscribed numeral 5,AONS node 1806 reads the message, selects and executes a flow, andremoves the AONP header from the message, formatting the messageaccording to the message format expected by a server 1808. Atcircumscribed numeral 6, AONS node 1806 sends the message to themessage's destination, server 1808.

According to the node view, the message lifecycle within an AONS node,involves ingress/egress processing, message processing, messageexecution control, and flow execution.

FIG. 19 is a diagram that illustrates message-processing modules withinan AONS node 1900. AONS node 1900 comprises an AONS message executioncontroller (AMEC) framework 1902, a policy management subsystem 1904, anAONS message processing infrastructure subsystem 1906, and an AOSS 1908.AMEC framework 1902 comprises a flow management subsystem 1910, abladelet™ execution subsystem 1912, and a message execution controller1914. Policy management subsystem 1904 communicates with flow managementsubsystem 1910. AOSS 1908 communicates with bladelet™ executionsubsystem 1912 and AONS message processing infrastructure subsystem1906. AONS message processing infrastructure subsystem 1906 communicateswith message execution controller 1914. Flow management subsystem 1910,bladelet™ execution subsystem, and message execution controller 1914 allcommunicate with each other.

FIG. 20 is a diagram that illustrates message processing within AONSnode 1900. AMEC framework 1902 is an event-based multi-threadedmechanism to maximize throughput while minimizing latency for messagesin the AONS node. According to one embodiment, received packets arere-directed, TCP termination is performed, SSL termination is performedif needed, Layer 5 protocol adapter and access method processing isperformed (using access methods such as HTTP, SMTP, FTP, JMS/MQ, JMS/RV,JDBC, etc.), AONS messages (normalized message format for internal AONSprocessing) are formed, messages are queued, messages are dequeued basedon processing thread availability, a flow (or rule) is selected, theselected flow is executed, the message is forwarded to the message'sdestination, and for request/response-based semantics, responses arehandled via connection/session state maintained within AMEC framework1902.

In one embodiment, executing the flow comprises executing each step(i.e., bladelet™/action) of the flow. If a bladelet™ is to be run withina separate context, then AMEC framework 1902 may enqueue intobladelet™-specific queues, and, based on thread availability, dequeueappropriate bladelet™ states from each bladelet™ queue.

3.4.10 Flows, Bladelets™, and Scriptlets™

According to one embodiment, flows string together bladelets™ (i.e.,actions) to customize message processing logic. Scriptlets™ provide amechanism for customers and partners to customize or extend native AONSfunctionality. Some bladelets™ and services may be provided with an AONSnode.

3.4.11 AONS Services

As mentioned in the previous section, a set of core services may beprovided by AONS to form the underlying foundation of value-addedfunctionality that can be delivered via an AONS node. In one embodiment,these include: Security Services, Standard Compression Services, DeltaCompression Services, Caching Service, Message Logging Service, PolicyManagement Service (Policy Manager), Reliable Messaging Service,Publish/Subscribe Service, Activity Monitoring Service, MessageDistribution Service, XML Parsing Service, XSLT Transformation Service,and QoS Management Service. In one embodiment, each AONS core service isimplemented within the context of a service framework.

3.4.12 AONS Configuration and Management

In one embodiment, an AONS node is provisioned and configured for aclass of application messages, where it enforces the policies that aredeclaratively defined on behalf-of the application end-points,business-domains, security-domains, administrative domains, andnetwork-domains. Furthermore, the AONS node promotes flexiblecomposition and customization of different product functional featuresby means of configurability and extensibility of different software andhardware sub-systems for a given deployment scenario. Due to theapplication and network embodiments of the AONS functionality, the AONSarchitecture framework should effectively and uniformly addressdifferent aspects of configurability, manageability, and monitorabilityof the various system components and their environments.

The AONS Configuration and Management framework is based upon fivefunctional areas (“FCAPS”) for network management as recommended by theISO network management forum. The functional areas include faultmanagement, configuration management, accounting management, performancemanagement, and security management. Fault management is the process ofdiscovering, isolating, and fixing the problems or faults in the AONSnodes. Configuration management is the process of finding and setting upthe AONS nodes. Accounting management involves tracking usage andutilization of AONS resources to facilitate their proper usage.Performance management is the process of measuring the performance ofthe AONS system components and the overall system. Security managementcontrols access to information on the AONS system. Much of the abovefunctionality is handled via proper instrumentation, programminginterfaces, and tools as part of the overall AONS solution.

FIG. 21, FIG. 22, and FIG. 23 are diagrams that illustrate entitieswithin an AONS configuration and management framework. A configuring andprovisioning server (CPS) is the centralized hub for configuration andmanagement of AONS policies, flows, scriptlets™ and other manageableentities. Configurable data is pushed to the CPS from an AONS designstudio (flow tool) and the AONS admin may then provision this data tothe production deployment. A promotion process is also provided to testand validate changes via a development to staging/certification toproduction rollout process. A configuration and provisioning agent (CPA)resides on individual AONS blades and provides the local control anddispatch capabilities for AONS. The CPA interacts with the CPS to getupdates. The CPA takes appropriate actions to implement changes. The CPAis also used for collecting monitoring data to report to third partyconsoles.

3.4.13 AONS Monitoring

In one embodiment, AONS is instrumented to support well-defined eventsfor appropriate monitoring and visibility into internal processingactivities. The monitoring of AONS nodes may be accomplished via apre-defined JMX MBean agent that is running on each AONS node. Thisagent communicates with a remote JMX MBean server on the PC complex. AnAONS MIB is leveraged for SNMP integration to third party consoles. FIG.24 is a diagram that illustrates an AONS monitoring architecture.

3.4.14 AONS Tools

In one embodiment, the following tool sets are provided for variousfunctional needs of AONS: a design studio, an admin studio, and amessage log viewer. The design studio is a visual tool for designingflows and applying message classification and mapping policies. Theadmin studio is a web-based interface to perform all administration andconfiguration functions. The message log viewer is a visual interface toanalyze message traffic, patterns, and trace information.

4.0 Implementation Mechanisms—Hardware Overview

FIG. 5 is a block diagram that illustrates a computer system 500 uponwhich an embodiment of the invention may be implemented. The preferredembodiment is implemented using one or more computer programs running ona network element such as a proxy device. Thus, in this embodiment, thecomputer system 500 is a proxy device such as a load balancer.

Computer system 500 includes a bus 502 or other communication mechanismfor communicating information, and a processor 504 coupled with bus 502for processing information. Computer system 500 also includes a mainmemory 506, such as a random access memory (RAM), flash memory, or otherdynamic storage device, coupled to bus 502 for storing information andinstructions to be executed by processor 504. Main memory 506 also maybe used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor504. Computer system 500 further includes a read only memory (ROM) 508or other static storage device coupled to bus 502 for storing staticinformation and instructions for processor 504. A storage device 510,such as a magnetic disk, flash memory or optical disk, is provided andcoupled to bus 502 for storing information and instructions.

A communication interface 518 may be coupled to bus 502 forcommunicating information and command selections to processor 504.Interface 518 is a conventional serial interface such as an RS-232 orRS-322 interface. An external terminal 512 or other computer systemconnects to the computer system 500 and provides commands to it usingthe interface 514. Firmware or software running in the computer system500 provides a terminal interface or character-based command interfaceso that external commands can be given to the computer system.

A switching system 516 is coupled to bus 502 and has an input interface514 and an output interface 519 to one or more external networkelements. The external network elements may include a local network 522coupled to one or more hosts 524, or a global network such as Internet528 having one or more servers 530. The switching system 516 switchesinformation traffic arriving on input interface 514 to output interface519 according to pre-determined protocols and conventions that are wellknown. For example, switching system 516, in cooperation with processor504, can determine a destination of a packet of data arriving on inputinterface 514 and send it to the correct destination using outputinterface 519. The destinations may include host 524, server 530, otherend stations, or other routing and switching devices in local network522 or Internet 528.

The invention is related to the use of computer system 500 for avoidingthe storage of client state on computer system 500. According to oneembodiment of the invention, computer system 500 provides for suchupdating in response to processor 504 executing one or more sequences ofone or more instructions contained in main memory 506. Such instructionsmay be read into main memory 506 from another computer-readable medium,such as storage device 510. Execution of the sequences of instructionscontained in main memory 506 causes processor 504 to perform the processsteps described herein. One or more processors in a multi-processingarrangement may also be employed to execute the sequences ofinstructions contained in main memory 506. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions to implement the invention. Thus, embodiments ofthe invention are not limited to any specific combination of hardwarecircuitry and software.

The term “computer-readable medium” as used herein refers to any mediumthat participates in providing instructions to processor 504 forexecution. Such a medium may take many forms, including but not limitedto, non-volatile media, volatile media, and transmission media.Non-volatile media includes, for example, optical or magnetic disks,such as storage device 510. Volatile media includes dynamic memory, suchas main memory 506. Transmission media includes coaxial cables, copperwire and fiber optics, including the wires that comprise bus 502.Transmission media can also take the form of acoustic or light waves,such as those generated during radio wave and infrared datacommunications.

Common forms of computer-readable media include, for example, a floppydisk, a flexible disk, hard disk, magnetic tape, or any other magneticmedium, a CD-ROM, any other optical medium, punch cards, paper tape, anyother physical medium with patterns of holes, a RAM, a PROM, and EPROM,a FLASH-EPROM, any other memory chip or cartridge, a carrier wave asdescribed hereinafter, or any other medium from which a computer canread.

Various forms of computer readable media may be involved in carrying oneor more sequences of one or more instructions to processor 504 forexecution. For example, the instructions may initially be carried on amagnetic disk of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to computer system 500 canreceive the data on the telephone line and use an infrared transmitterto convert the data to an infrared signal. An infrared detector coupledto bus 502 can receive the data carried in the infrared signal and placethe data on bus 502. Bus 502 carries the data to main memory 506, fromwhich processor 504 retrieves and executes the instructions. Theinstructions received by main memory 506 may optionally be stored onstorage device 510 either before or after execution by processor 504.

Communication interface 518 also provides a two-way data communicationcoupling to a network link 520 that is connected to a local network 522.For example, communication interface 518 may be an integrated servicesdigital network (ISDN) card or a modem to provide a data communicationconnection to a corresponding type of telephone line. As anotherexample, communication interface 518 may be a local area network (LAN)card to provide a data communication connection to a compatible LAN.Wireless links may also be implemented. In any such implementation,communication interface 518 sends and receives electrical,electromagnetic or optical signals that carry digital data streamsrepresenting various types of information.

Network link 520 typically provides data communication through one ormore networks to other data devices. For example, network link 520 mayprovide a connection through local network 522 to a host computer 524 orto data equipment operated by an Internet Service Provider (ISP) 526.ISP 526 in turn provides data communication services through theworldwide packet data communication network now commonly referred to asthe “Internet” 528. Local network 522 and Internet 528 both useelectrical, electromagnetic or optical signals that carry digital datastreams. The signals through the various networks and the signals onnetwork link 520 and through communication interface 518, which carrythe digital data to and from computer system 500, are exemplary forms ofcarrier waves transporting the information.

Computer system 500 can send messages and receive data, includingprogram code, through the network(s), network link 520 and communicationinterface 518. In the Internet example, a server 530 might transmit arequested code for an application program through Internet 528, ISP 526,local network 522 and communication interface 518. In accordance withthe invention, one such downloaded application provides for avoiding thestorage of client state on a server as described herein.

Processor 504 may execute the received code as it is received and/orstored in storage device 510 or other non-volatile storage for laterexecution. In this manner, computer system 500 may obtain applicationcode in the form of a carrier wave.

5.0 Extensions and Alternatives

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

1. A method of providing reliable delivery of an application layermessage, the method comprising the computer-implemented steps of:receiving one or more data packets at a first network element;determining a first application layer message that is collectivelycontained in one or more payload portions of the one or more datapackets, wherein the first application layer message originated at asource application; extracting, from the first application layermessage, a message identifier that is contained in the first applicationlayer message; determining whether a message identifier queue containsthe message identifier; and in response to determining that the messageidentifier queue does not contain the message identifier, storing thefirst application layer message in an application layer message queue aswell as storing the message identifier into the message identifier queueatomically, and sending towards the source application, anacknowledgment (ACK) message that indicates the message identifier;wherein the method is performed by one or more computing devices of thefirst network element located between the source application and adestination of the first application layer message.
 2. A method asrecited in claim 1 wherein the storing comprises storing in a persistentstorage device that is coupled to the router and coupled to thedestination.
 3. A method as recited in claim 1, further comprising: inresponse to determining that the message identifier queue contains themessage identifier, sending the acknowledgment (ACK) message toward thesource application without storing the first application layer messagein the application layer message queue.
 4. A method as recited in claim1, wherein the message identifier was added to the first applicationlayer message by a second network element that is separate from both thefirst network element and a device that hosts the source application. 5.A method as recited in claim 1, wherein receiving the one or more datapackets comprises intercepting the one or more data packets at the firstnetwork element, and wherein the one or more data packets are destinedfor a destination application rather than the first network element. 6.A method as recited in claim 1, wherein the first network element is anetwork switch or router.
 7. A non-transitory computer-readable volatileor non-volatile storage medium carrying one or more sequences ofinstructions for providing reliable delivery of an application layermessage, which instructions, when executed by one or more processors,cause the one or more processors to carry out the steps of: receivingone or more data packets at a first network element; determining a firstapplication layer message that is collectively contained in one or morepayload portions of the one or more data packets, wherein the firstapplication layer message originated at a source application;extracting, from the first application layer message, a messageidentifier that is contained in the first application layer message;determining whether a message identifier queue contains the messageidentifier; and in response to determining that the message identifierqueue does not contain the message identifier, storing the firstapplication layer message in an application layer message queue as wellas storing the message identifier into the message identifier queueatomically, and sending, towards the source application, anacknowledgment (ACK) message that indicates the message identifier;wherein the first network element is located between the sourceapplication and a destination of the first application layer message. 8.A non-transitory computer-readable volatile or non-volatile storagemedium as recited in claim 7, wherein instructions which cause thestoring comprise instructions which when executed cause storing in apersistent storage device that is coupled to the router and coupled tothe destination.
 9. A non-transitory computer-readable volatile ornon-volatile storage medium as recited in claim 7, wherein the stepsfurther comprise: in response to determining that the message identifierqueue contains the message identifier, sending the acknowledgment (ACK)message toward the source application without storing the firstapplication layer message in the application layer message queue.
 10. Anon-transitory computer-readable volatile or non-volatile storage mediumas recited in claim 7, wherein the message identifier was added to thefirst application layer message by a second network element that isseparate from both the first network element and a device that hosts thesource application.
 11. A non-transitory computer-readable volatile ornon-volatile storage medium as recited in claim 7, wherein receiving theone or more data packets comprises intercepting the one or more datapackets at the first network element, and wherein the one or more datapackets are destined for a destination application rather than the firstnetwork element.
 12. A non-transitory computer-readable volatile ornon-volatile storage medium as recited in claim 7, wherein the firstnetwork element is a network switch or router.
 13. An apparatus forproviding reliable delivery of an application layer message, comprising:a network interface for receiving one or more packet flows; a processor;a computer-readable volatile or non-volatile storage medium storing oneor more stored sequences of instructions which, when executed by theprocessor, cause the processor to carry out the steps of: receiving oneor more data packets; determining a first application layer message thatis collectively contained in one or more payload portions of the one ormore data packets, wherein the first application layer messageoriginated at a source application; extracting, from the firstapplication layer message, a message identifier that is contained in thefirst application layer message; determining whether a messageidentifier queue contains the message identifier; and in response todetermining that the message identifier queue does not contain themessage identifier, storing the first application layer message in anapplication layer message queue from which a destination application canretrieve the first application layer message, and sending, toward thesource application, an acknowledgment (ACK) message that indicates themessage identifiers; wherein the apparatus is located between the sourceapplication and a destination of the first application layer message.14. An apparatus as recited in claim 13, wherein the one or more storedsequences of instructions further comprise instructions which, whenexecuted by the processor, cause the processor to: identifier performthe storing in a persistent storage device that is coupled to the routerand coupled to the destination.
 15. An apparatus as recited in claim 13,wherein the one or more stored sequences of instructions furthercomprise instructions which, when executed by the processor, cause theprocessor to: in response to determining that the message identifierqueue contains the message identifier, sending the acknowledgment (ACK)message toward the source application without storing the firstapplication layer message in the application layer message queue.
 16. Anapparatus as recited in claim 13, wherein the message identifier wasadded to the first application layer message by a second network elementthat is separate from both the first network element and a device thathosts the source application.
 17. An apparatus as recited in claim 13,wherein receiving the one or more data packets comprises interceptingthe one or more data packets at the first network element, and whereinthe one or more data packets are destined for a destination applicationrather than the first network element.
 18. An apparatus as recited inclaim 13, wherein the first network element is a network switch orrouter.